The present invention relates to an image recording apparatus, and more particularly to a packing case for image recording sheets which are used in an image recording apparatus, such as a color hard copy machine.
U.S. Pat. Nos. 4,399,209 and 4,440,846 and U.K. Pat. No. GB 2,223,860 to Mead Corporation describe an imaging system. According to this system, a photosensitive layer comprising microcapsules containing a photosensitive composition in the internal phase is image-wise exposed to actinic radiation and subjected to a uniform rupturing force, whereby the microcapsules rupture and image-wise release the internal phase. An image-forming agent such as a substantially colorless chromogenic material is coated on an image recording sheet and is typically associated with the microcapsules such that when the microcapsules rupture, the chromogenic material is able to image-wise react with a developer material and produce a color image. Since this printing system can produce pixels in the same size as the size of a microcapsule, that is on the order of .mu.m, a color image is printed with extremely high resolution.
There are roughly two types of image recording sheets in terms of their storage and feeding systems. One is provided in a roll such as disclosed in the above U.S. patents. The other is provided in cut sheets. The cut sheet feed system is disclosed in, for example, EP 255,138A. Cut image recording sheets are generally provided in a large container box. Therefore when cut image recording sheets are set at a feeding station or feeding tray of an image recording apparatus, a required amount of cut image recording sheets is taken out from the large container box and thereafter set in the feeding station by hand.
This manual operation causes basically two problems. A front surface of a cut image recording sheet is coated with an image-forming agent, and therefore manual handling of the cut image recording sheets may likely damage the image-forming agent coated surface of the image recording sheet since the image-forming agent easily comes off from the surface of the sheet. Furthermore, even though the front surface of the image recording sheet is coated with an image-forming agent, the coating of the image-forming agent is not visibly discernible, and therefore the front surface of the sheet coated with the image-forming agent is easily mistaken for its rear surface.
Secondly, a conventional feeding tray 60 is shown in FIG. 50. A required amount of image-forming sheets is set into the feeding tray 60 before the feeding tray 60 is fitted into an image-forming apparatus, such as a color hard copy machine. Conventionally, such feeding tray has brushes on the inner surfaces thereof in order to prevent simultaneously feeding of the multiple image-forming sheets (hereafter referred to as double feeding). However, in case of the use of image recording sheets, such brushes are not preferable because bristles of the brushes scrape off the image-forming agent coated on the surface of the image-forming sheet.
A well known image-forming apparatus has an image recording sheet feeder such as schematically shown in FIG. 10A and FIG. 10B. When this image-forming apparatus adopts a conventional feeding tray such as shown in FIG. 50, another problem in addition to the problems described above occurs. The image recording sheet feeder basically uses sucking force of suckers for attracting an image recording sheet. The attracted image recording sheet is then fed in the image-forming apparatus. FIGS. 51(A) to 51(D) schematically show the operation of feeding an image recording sheet 1 by suckers 10. FIGS. 51(E) to 51(H) are perspective views showing successively the operation of feeding the image recording sheet 1 by the suckers 10. FIG. 51(A) shows a state, in which the image recording sheet 1 stored in a feeding tray 3 has its surface sucked by two suckers 10. FIG. 51(E) is a perspective view showing the sucked state of the image recording sheet 1 by the suckers 10 within a range of a portion K shown in FIG. 51(A). When the suckers 10 are slightly raised from the position shown in FIG. 51(A), the image recording sheet 1 has its peripheral portion caught by the inner walls of the feeding tray 3 due to the friction between the periphery of the image recording sheet 1 and the inner walls of the feeding tray 3 because the image recording sheet 1 and the shape of the storage space of the feeding tray 3 have substantially the same shape. As a result, the peripheral edge portion of the image recording sheet 1 does not rise as compared with the inner area of the image-recording sheet as shown in FIG. 51(B) which results in a curve L around the peripheral portion of the image recording sheet as shown in FIG. 51(F). When the suckers 10 are raised to a height shown in FIG. 51(C), the curve L extends to a position under the suckers 10 as shown in FIG. 51(G) and the attracting force between the suckers 10 and the image recording sheet is consequently reduced. When the suckers 10 are further raised, the attracting force between the image recording sheet 1 and the suckers 10 is lost, and consequently the image recording sheet drops back into the feeding tray 3 as shown in FIGS. 51(D) and 51(H). In particular, when the humidity around the image-recording sheet 1 is high, the image-forming agent coated on the image recording sheet increases its resistance, whereby the problem accompanying this sheet feeder as described above worsens.
Thirdly, in sheet prior art, the detection is performed by providing a detection unit in a sheet conveyor path inside of the image-recording apparatus. This art repeats purposeless operations of feeding the sheets to the inside of the image recording apparatus until the detection unit judges the exhaust of the sheets despite the fact that the sheets have already been exhausted. In order to prevent such purposeless operations, it has been conceived to provide in the case a mechanism for raising the sheets so that the existence of the sheets may be determined by a touch sensor. For example, FIG. 52 is a schematic section showing a paper feed unit of the prior art. Sheets 61 are packed in a feeding tray 60 which is arrange therein with a pop-up plate 62, and this plate 62 is popped up by the extension of a spring 63. Over the surface of the feeding tray 60, there is arranged a roller 64 which is made of silicon rubber for conveying the sheets 61 into an image-recording apparatus 66. At the end of the sheet 61, there is arranged a touch sensor 65 for detecting the existence of the sheets 61. The touch sensor 65 has its two ends 65B and 65C pivotal on a fulcrum 65A so that when all the sheets 61 are conveyed out from the feeding tray 60, a detection unit 65D comes into contact with the end 65C to inform the image-recording apparatus 66 itself or its user of the exhaustion of the sheets 61. Thus, the image-recording apparatus of the prior art can not recognize the exhaustion of the image recording sheets, and continues its feeding and printing operations without image recording sheets. Such operation may damage components provided within the image-recording apparatus such as suckers, pressure rollers, etc.
Fourthly, an image-recording apparatus of the prior art has a feeding station whose width is manually adjusted for accommodating image recording sheets of different sizes. The change of sheet size is detected with a sheet-size detection unit provided within the image-recording apparatus, and the pressure of the pressure rollers is adjusted according to the detected change in size of the image-recording sheet. Therefore there is likelihood of wrong feeding of an image-recording sheet of a size inappropriate for a manually set sheet size. When an inappropriate sheet is fed, components such as pressure rollers provided within the image-recording apparatus may be damaged due to improper roller pressure for a fed image recording sheet.